Hydraulicking

Placer gold is that which is loose in the soil and closest to the surface. Placer mining requires water to wash the dirt, perseverance, and a strong back. Gold is the heaviest material in the soil, and so in the process of washing, the heavy gold is the residue remaining in the pan or the sluice box. The rich goldfields that drew miners to Montana in the mid-1860s only held so much placer gold. Miners wanted to be sure to extract all of it, and so when that closest to the surface was depleted...